Synthesis, Characterization, and Novel Redox Properties of a New Triply Bridged Dimanganese(III) Complex with a {MnIII2(.mu.-O)(.mu.-O2CCH3)2}2+ Core

Abstract

Oxo-bridged clusters of manganese1•* 12 have been shown to occur in the active sites of the catalases, /weudocatalases, ribonucleotide reductases, and the photosynthetic water oxidation center. The synthetic complexes with structural units { 2(µ-0)(µ-02-CCH3)2}2+3"5 and { (µ-0)2(µ-02€€ 3)}2+ 6•7 are of current interest since they are good models for these enzymes.It has been shown3 4•48•6•6*•8 that ^-oxo)bis^-acetato)dimanganese-(III) complexes could be oxidized by following two pathways:(i) sequential electrochemical oxidation to MnmMnIV and MnIV2 oxidation levels and (ii) chemical transformations to {Mnm-(µ-0)(µ-)2}3+ and { (µ-0)2(µ-3 )}2+ species. It is interesting to note that while disproportionation of the {Mn111-(µ-0)2}3+ core under acidic conditions has been postulated previously,9•10 *11to our knowledge isolation of a 2(µ-0)(µac)2}2+ species from a { (µ-0)2(µ-)}2+ species has not so far been achieved.We recently reported7 an antiferromagnetically coupled dimanganese complex [ (µ-)2(µ-20 6)( ߣ.)2] (Cl-04)2• 20 (1) using MeL as a facially capping ligand [MeL = f Dedicated to Professor Richard H. Holm on the occasion of his 60th

Redox‐Induced μ‐Acetato and μ‐Oxo Core Interconversions in Dinuclear Manganese Tris(2‐methylpyridyl)amine (tpa) Complexes: Isolation and Characterization of [Mn2III(μ‐O)(μ‐O2CCH3)(tpa)2]3+

“…[Equation (3)], which reacts with residual water in the solvent [25][26][27][28][29]43] to form the binuclear complex 3 3+ by substitution of one acetato bridge by an oxo bridge [Equation (6)]. (6) However, since 3 3+ is more easily oxidizable than 2…”

Rationalizing the sign and magnitude of the magnetic coupling and anisotropy in dinuclear manganese(iii) complexes

“…[25][26][27] To mimic this enzyme, several dinuclear Mn III complexes with a [Mn2(μ-O)(μ-RCOO)2] 2+ core have been reported in the literature, and, in some cases, they have been magnetically and structurally characterized. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Due to its large single ion anisotropy, the Jahn-Teller distorted Mn III ion is the preferred d-block ion of choice for the synthesis of single-molecule magnets (SMMs). [2][3][4][5]51 To design SMMs it is preferable to have strong ferromagnetic exchange between neighbouring metal centres and finding out what controls the magnitude and sign of the pairwise magnetic exchange is essential.…”

Cationic Methyl(hydrido)platinum(IV) Complexes

“…The ligand bis(2-pyridylmethyl)amine, BPMA, was chosen to test this hypothesis. First prepared by Larsen to study structural and magnetic properties of dimeric chromium(III) complexes, it and related ligands have also been used in structural studies of ruthenium(II) “piano-stool” complexes and in oxo-bridged complexes of manganese(III) .…”